[meteorite-list] 1993/94 Perseids - The Night of Lights!

From: David Pensenstadler <dfpens01_at_meteoritecentral.com>
Date: Sat, 14 Aug 2010 12:53:01 -0700 (PDT)
Message-ID: <419356.53684.qm_at_web113320.mail.gq1.yahoo.com>

Pittsburgh area was clear for the first time in years for the Perseids. Took my 10 year old granddaughter out and we observed until about 2:30 am. Saw a total of 24. My horizon is fairly high and so we could only observe from Cassiopea through Pegasus to Cygnus and a bit south of those constellations - a very limited area of sky. Bright lights of Pittsburgh wash out anything west.

These were the first meteors that my granddaughter has ever seen and she said they were "awesome".

Back in the mid-80's, I remember making counts of more than 150 per hour from a dark location away from city lights.

Dave





--- On Sat, 8/14/10, bernd.pauli at paulinet.de <bernd.pauli at paulinet.de> wrote:

> From: bernd.pauli at paulinet.de <bernd.pauli at paulinet.de>
> Subject: [meteorite-list] 1993/94 Perseids - The Night of Lights!
> To: Meteorite-list at meteoritecentral.com
> Date: Saturday, August 14, 2010, 7:54 AM
> Hello List,
>
> Some of you may have been surprised when they read about
> more than
> 300 Perseids in the Sky & Telescope article I mentioned
> last night:
>
> 'Counts made from western Europe, the Canary Islands, and
> eastern North
> America indicate the maximum zenithal hourly rate (ZHR)
> topped out at
> more than 300 around 3:30 Universal Time on August 12th.'
>
> This would make Kirk's and his friends' observation of 100
> and even Greg's
> 183 look rather "average" but it's not like that at all
> because ZHR is the
> total number of meteors an experienced observer with an
> incredible 360? view
> would see under ideal conditions.
>
> Let's see how ZHR > 300 translates into what was
> actually observed, i.e. the
> actual HR (hourly rate or actual number of meteors
> observed). The formula for
> computing the actual number is:
>
> ZHR = HR x? r^ (6.5-LM) / sinA
>
> r = usually 2.5 for the Perseids (called population index)
> 6.5 = a real dark sky (limiting magnitude of stars you can
> see)
> LM = limiting magnitude in the part of the sky being
> watched
> A = the altitude of the shower's radiant
>
> Assuming almost ideal conditions (on the Canary Islands for
> example),
> let's use LM = 6 and an altitude of 60? of the Perseid
> radiant (around
> 01:00 hrs after midnight), ... so we have:
>
> 300 = HR x 2.5^ (6.5-6.0) / sin 60?
> 300 = (HR x 2.5^0.5) / sin 60?
> 300 = (HR x 1.58) / 0.87
> HR = (300 x 0.87) / 1.58
> HR = 261 / 1.58
> HR = 165
>
> That's the actual number a single experienced person may
> have been able
> to see under favorable conditions, so Greg's Lindh's number
> (HR = 183) is
> quite close to that mathematical result and Kirk's and his
> friends' HR of
> 100 Perseids is still a very respectable number of
> meteors!
>
> Happy Computing,
> Happy Observing,
> Clear Skies,
>
> Bernd :-)
>
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Received on Sat 14 Aug 2010 03:53:01 PM PDT